In previous studies, we described a method for detecting and typing malignant tumors of the thyroid gland in fine-needle aspiration biopsy samples via analysis of a molecular marker panel (normalized HMGA2 mRNA level; normalized microRNA-146b, -221, and -375 levels; mitochondrial-to-nuclear DNA ratio; and BRAFV600E mutation) in cytological preparations by quantitative PCR. In the present study, we aimed to estimate the specificity of the typing of different thyroid tumors by the proposed method. Fine-needle aspiration cytological preparations from 278 patients were used. The histological diagnosis was known for each sample. The positive and negative predictive values of the method assessed in this study were, respectively, 100% and 98% for papillary thyroid carcinoma (n = 63), 100% and 100% for medullary thyroid carcinoma (n = 19), 43.5% and 98% for follicular carcinoma (n = 15), and 86% and 100% for Hürthle cell carcinoma (n = 6). Thus, we demonstrate that the diagnostic panel, including the analysis of microRNA expression, mRNA expression, the BRAFV600E mutation, and the mitochondrial-to-nuclear DNA ratio, allows the highly accurate identification of papillary thyroid carcinoma, medullary thyroid carcinoma, and Hürthle cell carcinoma but not malignant follicular tumors (positive predictive value was below 50%).

The preoperative diagnostics of medullary thyroid carcinoma (MTC), including the measuring of the blood calcitonin level, has a number of limitations. Particular focus has recently been placed on the role of miRNAs in the development of various malignant tumors; a comparative analysis of accuracy of the existing methods for MTC diagnosis with a novel diagnosis method, evaluation of the miRNA-375 expression level, was performed in this study. The expression level of miRNA-375 in cytology samples from 555 patients with the known histological diagnosis, including 41 patients with confirmed postoperative diagnosis of MTC, was assessed. The diagnostic parameters of the basal calcitonin level, calcitonin in wash-out fluid from the FNAB needle, and miRNA-375 were compared. An assessment of the miRNA-375 expression level made it possible to detect all the MTC samples with a 100% accuracy among all the 555 cytology specimens, as well as in non-informative FNAB specimens, and specimens from the ipsilateral thyroid lobe. Parameters such as sensitivity, specificity, PPV, and NPV were 100%. The miRNA-375 level, unlike calcitonin, does not correlate with tumor volume, so it does not have the so-called “gray zone”. An assessment of the miRNA-375 expression allows one to accurately distinguish MTC from other malignant and benign thyroid tumors.

Introduction. Fine needle aspiration biopsy followed by cytological examination is the gold standard in the diagnosis of thyroid nodules. However, up to one third of cases represent an indeterminate result (Bethesda Thyroid Classification, 2017) III—V). Among such cases, category IV is the most common and most difficult to interpret (Bethesda, 2017). The study objective is to determination of the diagnostic and prognostic significance of the molecular genetic study of the fine needle aspiration biopsy material in patients with thyroid nodules with the cytological category Bethesda, IV.Materials and methods. The study included surgical thyroid samples obtained from patients whose cytological examination revealed pathology of cytological category IV according to the Bethesda classification (2017). group 1 included surgical samples from 143 patients with thyroid lesions, and group 2 - cytological material from 45 patients. Determination of the BRAF V600E mutation, mutations in the RAS genes (KRAS, HRAS, NRAS) was carried out using allele-specific polymerase chain reaction, and the RET / PTC1, RET / PTC3 and PAX8 / PPARG translocations were determined using reverse transcription polymerase chain reaction. Sanger sequencing was used to detect mutations in the promoter region of the TERT gene.Results. In group 1, an overall prevalence of the studied mutations in thyroid cancer was 35.1 %: 8.8 % of cases were mutation BRAF V600E, 24.6 % - mutations in the RAS genes, 1.8 % - mutation C228T in the TERT gene. The C228T mutation in the TERT gene was found in 1 case of widely invasive Hurtle cell carcinoma. The prevalence of mutations in benign formations was 4.7 %. mutations in RAS genes were also found in them in group 1, mutation BRAF V600E was associated with the presence of extrathyroid invasion (p = 0.024), vascular invasion (p = 0.018), and lymph node metastases (p = 0.018). In group 2, using the genetic panel sensitivity and specificity were equal: 36.4 and 93.9 %, respectively. positive and negative predictive values were 66.7 and 81.6 %, respectively. No RET / PTC and PAX8 / PPARG translocations were found in groups 1 and 2.Conclusion. The investigated molecular genetic panel, having a high specificity for carcinomas, will make it possible to supplement the cytological diagnostics of material in the category Bethesda, IV. BRAF V600E was associated with an aggressive morphological pattern.

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Background. Urothelial carcinoma (UTC) is an aggressive disease with a known propensity for frequent recurrence. It is difficult to predict the velocity of the development of UTC recur using modern means of clinical diagnostics. Therefore, the development of the capabilities of histo-morphological study of tumor tissues is of particular relevance.Materials and methods. The materials of publications (PubMed, CrossRef) for 1990-2021, devoted to the choice of biomarkers for the diagnosis of UTC, the analysis of molecular pathways, progression and metastasis, were studied. The search was carried out for the key phrases "urothelial carcinoma", "recurrent UTK", "stem cells", "biomarkers of bladder cancer", "genetic changes in urothelium", "circulating tumor DNA".Results. Cancer stem cells serve as a source of UTC recurrence after removal from the primary focus, localizing in any areas of the urothelium, as well as outside the main tumor focus and are characterized by a common genotype, but different phenotypic manifestations. To predict the recurrence of the tumour is advisable to use gene expression signatures, since the subtypes of UTC are characterized by clear gene expression profiles. A larger sample and independent dataset is needed to confirm the clinical significance of the findings. Combined biomarkers predict UTC behavior, and FGFR3 and TP53 mutations can be components for a panel for predicting UTC recurrence. The use of the liquid biopsy method with the determination of the level of circulating tumor DNA is a promising diagnostic method that needs to evaluate the results of an initiated randomized trial.Conclusion. The accumulation of knowledge base about the molecular patterns of UTC will help bridge the gap between the results of molecular genetic and clinical diagnostics. Molecular changes in the transitional cell UTC demonstrates a high potential for determining the timing of tumor recurrence, assessing disease-free survival of patients and for planning the resource base of the healthcare system.